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Title: Extended Radial Reflector Modeling Capabilities in MPACT

 [1];  [1];  [1];  [2];  [3]
  1. ORNL
  2. Westinghouse Electric Company, Cranberry Township
  3. Westinghouse Electric Company LLC
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Consortium for Advanced Simulation of LWRs (CASL)
Sponsoring Org.:
OSTI Identifier:
DOE Contract Number:
Resource Type:
Resource Relation:
Conference: 2017 M&C Conference, Jeju Island, South Korea, 20170416, 20170420
Country of Publication:
United States

Citation Formats

Stimpson, Shane G, Collins, Benjamin S, Godfrey, Andrew T, Franceschini, Fausto, and Salazar, David. Extended Radial Reflector Modeling Capabilities in MPACT. United States: N. p., 2017. Web.
Stimpson, Shane G, Collins, Benjamin S, Godfrey, Andrew T, Franceschini, Fausto, & Salazar, David. Extended Radial Reflector Modeling Capabilities in MPACT. United States.
Stimpson, Shane G, Collins, Benjamin S, Godfrey, Andrew T, Franceschini, Fausto, and Salazar, David. Sun . "Extended Radial Reflector Modeling Capabilities in MPACT". United States. doi:.
title = {Extended Radial Reflector Modeling Capabilities in MPACT},
author = {Stimpson, Shane G and Collins, Benjamin S and Godfrey, Andrew T and Franceschini, Fausto and Salazar, David},
abstractNote = {},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2017},
month = {Sun Jan 01 00:00:00 EST 2017}

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  • The near-core radial shield in some advanced liquid metal fast reactors (LMRs) consists of steel reflector assemblies that surround the inner core assemblies followed by shield assemblies that have large volume fraction of boron carbide. The reflector and shield assemblies of these reactors are removable, similar in outer configuration to the inner core assemblies and link the inner assemblies to the outer parts of the core restraint system. An important design goal for these reflector and shield assemblies is to have the longest service life in the core with minimum handling. Extended residence of the reflector assemblies in particular, withmore » the ducts subjected to large neutron flux gradients, could give rise to relatively large differential irradiation-induced swelling strains, duct inelastic deformations and interassembly forces. The purpose of this paper is to assess the effect of extending the residence of reflector assemblies in view of the mechanical design requirements of LMR cores. 6 refs., 7 figs.« less
  • An analysis is performed to determine the effect of disassembling the radial reflector of the TOPAZ-II reactor, following a hypothetical severe Reactivity Initiated Accident (RIA). Such an RIA is assumed to occur during the system start-up in orbit due to a malfunction of the drive mechanism of the control drums, causing the drums to rotate the full 180[degree] outward at their maximum speed of 1.4[degree]/s. Results indicate that disassembling only three of twelve radial reflector panels would successfully shutdown the reactor, with little overheating of the fuel and the moderator.
  • This paper presents a work-flow for computing an equivalent 2D radial reflector in a pressurized water reactor (PWR) core, in adequacy with a reference power distribution, computed with the method of characteristics (MOC) of the lattice code APOLLO2. The Multi-modelling Equivalent Reflector Computation (MERC) work-flow is a coherent association of the lattice code APOLLO2 and the core code COCAGNE, structured around the ADAO (Assimilation de Donnees et Aide a l'Optimisation) module of the SALOME platform, based on the data assimilation theory. This study leads to the computation of equivalent few-groups reflectors, that can be spatially heterogeneous, which have been comparedmore » to those obtained with the OPTEX similar methodology developed with the core code DONJON, as a first validation step. Subsequently, the MERC work-flow is used to compute the most accurate reflector in consistency with all the R and D choices made at Electricite de France (EDF) for the core modelling, in terms of number of energy groups and simplified transport solvers. We observe important reductions of the power discrepancies distribution over the core when using equivalent reflectors obtained with the MERC work-flow. (authors)« less
  • A one-dimensional method based on a combination of the nodal equivalence theory and response matrix homogenization methods was previously described for determining environment-insensitive equivalent few-group diffusion theory parameters for homogenized radial reflector nodes of a pressurized water reactor. This reflector model, called the NGET-RM model, yields equivalent nodal parameters that do not account for the two-dimensional structure of the baffle at core corners; this can lead to significant errors in computed two-dimensional core power distributions. A semi-empirical correction procedure is proposed for reducing the two-dimensional effects associated with this particular one-dimensional reflector model. Numerical two-group experiments are performed for amore » given reflector configuration (and soluble boron concentration) to determine optimal values of the two empirical factors defined by this model. In this paper it is shown that the resultant factors are rather insensitive to core configuration or core conditions and that their application yields improved two-group NGET-RM reflector parameters with which accurate nodal power distributions can be obtained. The results are also compared with those obtained with another one-dimensional environment-insensitive model that has an extra degree of freedom utilized here to reduce two-dimensional effects. Some practical aspects related to the application of the proposed correction procedure are briefly discussed.« less